Question

Design a concrete mix using ACI Method required for an exterior column to be located above ground level in an area where it will be wet and subjected to substantial freezing and thawing. The concrete is required to have an average 28-day compressive strength of 30 MPa. For the conditions of placement, the slump should be between 25 and 100 mm. The column is 300 mm square with a minimum clear space for aggregate of 50 mm. The properties of the materials are as follows:

This value takes into account the difference between the average strength required and the specified design

• Cement:

• Type I,
• Specific gravity = 3.15

• • Fine aggregate:

• Bulk specific gravity (SSD) = 2.85;
• Absorption capacity = 1.96%;
• Surface moisture = 3.3% based on SSD state;
• Fineness modulus = 2.75

• Coarse aggregate:

• Maximum size = 34 mm;
• Bulk specific gravity (SSD) = 2.99;
• Absorption capacity = 1.69%;
• Surface moisture = 0.8% based on SSD state;
• Dry-rodded unit weight = 1550 kg/m³

Answer 1

Complete mix design and final mix proportion for given specifications is shown below.